1. Field of the Invention
The present invention relates to a baler for forming rectangular bales from harvested crop and including a baling channel having an inlet opening, a pressure piston reciprocating in the baling channel and periodically closing and opening the inlet opening of the baling channel, a continuously driven rake conveyor for delivering the harvested crop through the inlet opening of the baling channel synchronously with the reciprocating movement of the pressure piston, and an overload clutch for separating the rake conveyor from its drive upon overload of the rake conveyor for a delivery time period and for automatically connecting the rake conveyor with its drive upon expiration of the delivery time period.
2. Description of the Prior Art
An important precondition for forming uniform, high-density square bales is an adequate filling of the baling chamber or channel. An adequate filling should be insured with both thin swaths containing little crop and thick swaths containing a large amount of crop, and at different operational speeds. Only in this case, desired density and shape of bales can be obtained. Prior art discloses a number of solution for effecting an adequate filling of the baling channel.
German Publication DE 2748594 A1 discloses a method and an apparatus for loading of the crop with a continuously driven rotary conveyor and with a stuffer means for pushing a packing into the baling channel, with the conveyor being actuated by a single turn coupling, and driven synchronously with the pressure piston. Here, it is important that during the formation of bales, always, crop packages, which have as uniform size as possible be pushed into the baling channel. At the underside of the baling channel, there is provided a delivery channel which is closed by the rotary conveyor and serves as a storage space. The stuffer means is only then actuated by a claw coupling when the density probe in the delivery channel generates a signal indicating that a crop package with a desired size and/or thickness has been provided, and the baling channel opening is open by the pressure piston.
If the apparatus operates at a full capacity and a large-volume swath and/or at a greater speed, at the beginning of each piston cycle, a complete load of the crop is provided, and the stuffer means operates without interruptions. When the swath is small and the crop is moistened, from three to five pressure piston strokes (idle strokes) take place per a single stroke of the stuffer means. The drawback of the apparatus disclosed in DE 2748594 A1 consists in that as an overload clutch, which protects the stuffer means from overload, a shear bolt is used, with all of its known drawbacks.
In a baler which is disclosed in German Publication DE 4216483 A1, the rotary conveyor and the stuffer means are integrated in a single unit with a rake conveyor having an overload clutch. The overload clutch separates the rake conveyor from its drive for a time period corresponding to the time period of the pressure piston stroke when a predetermined load of the rake conveyor is exceeded by an amount corresponding to the response torque of the clutch. A serious drawback of this baler consists in that with thin swath containing little crop, an insufficient amount of crop accumulates in the delivery channel. As a result, the filling of the upper region of the baling channel is poor, and "banana"-shaped bales are formed.
German Publication DE 19627397 suggests that the rake conveyor of DE 4216483 A1 be driven, when the swath is thin, with a rotational speed equal to a half of the rotational speed of the crank drive of the pressure piston. i.e., the pressure piston performs two strokes per each delivery stroke of the rake conveyor, with one stroke of the pressure piston being, thus, idle. To provide for the reduction of speed of the rake conveyor, switch gear is of no use.
Accordingly, an object of the present invention is to improve the filling of the baling channel of the baler, which is disclosed in German Publication DE 4216483 A1, in particular with a thing swath with little material, without substantially changing the conveying and/or stuffer means, and to provide for use of the invention with stuffer means having either controllable or uncontrollable rakes. Another object of the present invention is to provide simple control means for operating the units of the baler according to the present invention.